Tool-shank.



G. E. HAGKETT.

TOOL SHANK. APPLICATION FILED PEB. 24, 1910.

0. 1 9 l wf. 2 LU. w. S M .m e .ab a D1 2 SHEETS-SHEET 1.

La AT oRNEY 'Y i li;

sans ra GEORGE E. HACKETT, OF NW YORK, N. Y.

TOOL-SHANK.

Specification of Letters Patent.

Patented Sept. 27, 1910.

To all whom it 'may concern:

Be it known that I, GEORGE E. HAcKn'r'r, a citizen of 'the United States of america, and a resident of New York, county and State of New York, have invented certain new and useful Improvements in Tool- Shanks, of which the following is a specification, reference being had to the accompanying drawings, forming a part thereof.

My invention relates 'to improvements 1n tools in the nature of twist drills, cutters, and the like, which are provided with shanks, usually of tapered form, for insertion in a socket, and which are subjected to longitudinal and torsional stress, and my invention consists in providing such a tool shank with weakened portions whereby the sections between them may be moved with relation to each other under the iniiuence of longitudinal or torsional stress, or both, so as to produce a distortion of the shank such as will cause it to the more intimately engage the walls of the socket.

In a previous Patent No. 898,162, which was granted 'to me July 141, 1908, a drill is shown and described in which the shank expands generally under longitudinall or torsional stress, and in a copending application, Serial Number 540,122 filed January 26, 1910, I have shown another application of the same principle, but the present structure differs therefrom in that the shank instead of expanding generally for the purpose of the more intimately engaging the walls of the socket under stress, becomes distorted for this purpose, and under these conditions portions only of the outer periphery of the shank will be caused to the more intimately engage the walls of the socket instead of substantially all of the peripheral portions thereof as in the pa'teiit and application above referred to.

The weakening of portions of the tool shanks for the above purpose may be accomplished by a plurality of parallel transverse cuts which extend inward from the outer periphery, preferably upon opposite sides of the tool shank. Such a construction results in dividing the tool shank as a whole into a plurality of sections which are adapted under torsional stress to be moved to positions out of line with each other, z'. c., axially eccentric, or under longitudinal stress to positions tipped or caiited with respect to each other, 2'. e., axially oblique.

In some cases I may ll in the openings made by the 'transverse cuts with a'relative soft metal, such as will tend to reinforce the weakened structure and yet will yield sufficient to permit the required movement, it being understood, of course, that the required movement is in any event an exceedingly small one, for the reason that the tool shank is designed to substantially fit the shank before it is distorted.

My invention also consists in weakening the tool shank by unevenly hardening the same,-that is to say, portions of the tool shank will be tempered to a greater degree than other portions. This part of my invention is applicable not only to tool Shanks of the foregoing description in which the several sections thereof are distorted relatively for the purpose specified, but is also applicable to other forms of tool shanks in which the stress in use produces an expansion thereof.

My invention also consists in a means for preventing an excess of relative movement of the parts under torsional stress consisting of means for positively locking the parts against other than limited relative movenient, and in further novel details of construction and combinations of parts, such as will be fully pointed out hereinafter, and in order that my invention may be thoroughly understood I will now proceed to describe certain embodiments thereof, having reference to the accompanying drawings illustrating the same, and will then point out the novel features in claims.

In the drawings: Figure 1 is a view in central longitudinal section through a tool shank constructed in accordance with my invention. F ig. 2 is a view in side elevation of the same, the point of view being taken at right angles to the point of View of Fig. 1. Fig. 3 is a transverse sectional view upon the plane of the line 3 8 of Fig. 1. Fig. 4lis a longitudinal sectional view similarv to Fig. 1, showing the tool shank as provided with lines of weakness which are differently disposed to those of the construction of Figs. 1 and 2, and showing the tool as fitted to a socket. Fig. 5 is a view in side elevation of the form of tool shank shown in Fig. 4, the point of view thereof being at right angles to t-he point of view of Fig. 4. Figs. G and 7 are diagrammatic views giving an exaggerated illustration of the distortion which takes place under torsional stress. Fig. S is a diagrammatic view giving an exaggerated illustration of the distortion which takes place under longitudinal stress. Fig. 9 is a view in longitudinal section of the form of tool shank shown in Figs. 1, 2 and 3, in which the weakened portions have been filled up with another metal and in which positive locking means for preventing other than limited relative movements under torsional stress has been omitted. Fig. 10 is a view in lonl gitudinal section through a tool shank in which certain portions have been tempered to a greater extent than other portions.

The class of tool illustrated in the drawings to which my improvements have been applied, is a twist drill comprising a body portion 10 and a shank 11. The shank 11 is shown as of general conical form, the extremity thereof being provided with a flattened portion 12 to constitute a tang. A socket is provided for receiving the shank having an interior wall of conical form arranged to substantially fit the shank, and provided at its inner end with a recess 14 to receive the tang. The coengagement of the tang with the recessed portion 14 serves to hold the inner end of the shank positively against rotation under torsional stress in use. The drill and socket so far described are well known in the art, being in common use in machine shops at the present day. In carrying out my invention I divide such a tool shank into a plurality of sections by providing lines of weakness along the shank between the sections. In Figs. 1, Q, and 3 these lines of weakness comprise a plurality of transverse cuts which extend inwardly from the outer periphery of the shank, the adjacent cuts extending inwardly from opposite sides of the said shank, as will be well understood by reference to the drawings. The remaining portions of the metal which connect the sections will act as eccentric connecting elements such as will cause the various sections to move to positions axially eccentric with respect to each other under a torsional stress, as is illustrated in the diagrammatic view Figs. G and 7. This distortion will cause the opposite faces of adjacent sections to move relatively so as to more intimately engage the walls of the socket. In order to prevent other than an exceedingly limited relative movement of the parts and to reinforce the parts to compensate to a certain extent for the weakness caused by the cuts 15, I conveniently provide this form of tool shank with longitudinally disposed pins 1 which are loosely fitted in longitudinal bores 17 provided to receive them. The amount of movement permitted will be limited by the play allowed between the pins and the walls of the bore 17. IVhen such limit has been reached the walls of the bores coming in contact with the pins therein will prevent further relative movements of the sections.

I conveniently provide means at the inner extremity of the shank for reinforcing the action of the tang for holding the inner end of the shank against rotation. This means may conveniently comprise projections 19 of any suitable form located within the inner end of the socket and arranged for coengagement with slots 20 in the inner end of the shank. These slots may, as a matter of construction, be in line with the bores 1T for receiving the pins 16, being formed as continuations thereof.

Under longitudinal stress the parts will tend to be canted or tipped with respect to each other, as is shown in a much exaggerated form in the diagrammatic View Fig. 8, and in this case the diagonally opposite edges of the sections will be caused to intimately engage the walls of the socket, as will be readily understood.

In Figs. 4 and 5 I have shown the oppositely disposed transverse cuts as arranged obliquely with respect to the plane containing the axis of the tool instead of at right angles thereto, as in the form shown in the Figs. 1, 2 and 3. The longitudinal pins 16 may also be employed in this structure, if desired, but in any event, it will be understood that the oblique faces of the cuts will meet each other after limited movement of the sections, whereby further movement of the sections will thus be prevented. In this structure, therefore, the pins if employed, will act more in the nature of a longitudinal reinforcement.

In Fig. 9 I have shown the transverse cuts of the construction shown in Figs. 1, 2 and 3, as lled in as at 21 with a relatively soft metal such as copper. Such a metal will be soft and ductile enough to permit the required relative movement of the parts, yet will tend to give a stronger structure than where the cuts are left open.

In Fig. 10 I have shown the line of weakness as provided by raising or lowering the temper of the metal at different points 18. This portion of my invention is capable of being applied to various forms of tool shanks adapted under longitudinal or torsional stress or both, to grip the walls of the socket to an increasing extent.

vWhat I claim is:

1. A tool shank comprising a plurality of concentric sections provided with eccentric connecting portions joining them together.

2. A tool shank having a portion provided with means whereby it may be retained against rotation in a socket, and a portion nearer the tool body capable of limited rotational movement under torsional stress, the said shank being provided with an eecen trically disposed part for connecting the two said portions together.

3. A tool shank having a plurality of oppositely disposed transverse cuts therein which partially sever the same, leaving` the remaining portions connected together by eccentrically disposed connecting elements.

4. A tool shank comprising a plurality of substantially rigid sections yieldingly connected together, and means for positively limiting the relative movements permitted between the sections.

5. A tool shank having a plurality oit transversely arranged lines of weakness therein, the portions between the lines of weakness being rigid, whereby the weakened portions will yield to permit slight relative movements of the rigid portions with respect to each other, and having means for positively limiting the relative movements permitted between the said rigid portions.

6. A tool shank comprising a plurality ot' substantially rigid sections yieldingly connected together, whereby stress upon the shank will tend to relatively distort the sections, and provided with means for limiting the distorsional movements permitted to the said sections.

7 A tool shank comprising a plurality of concentric sections provided with eccentric connecting portions joining them together, and means for positively limiting the relative movement of the said concentric sections about their eccentric connecting portions.

8. A tool shank having a transverse cut therein which partially severs the same, whereby stress upon the shank will cause a relative movement of the two parts upon opposite sides of the said cut, and having means for positively limiting such relative movements of the two parts.

9. A tool shank having a portion provided with means whereby it may be retained against rotation in a socket, and a portion nearer the tool body capable of limited rotan tional movement under torsional stress, the said shank being provided with an eccentrically disposed part for connecting the two side portions together, and with means for positively limiting the relative movement of the two said portions.

l0. A tool shank comprising a plurality of concentric sections provided with eccentric connecting portions joining them together, and longitudinally disposed pins :tor limiting the movement of the said sections about their' connecting portions.

l1. A tool shank having a transverse cut therein which partially severs the same, whereby stress upon the shank will cause a relative movement of the two parts upon opposite sides of the said cut, and a longitudinal pin loosely disposed in the said shank and which crosses the said cut.

12. A tool shank having a plurality of oppositely disposed transverse cuts therein and having two longitudinal bores which pass through the cuts, and pins loosely disposed within the said bores.

13. A tool shank having parts relatively movable under working stress, and provided with means for positively limiting such movements.

14. A tool shank having parts relatively movable laterally under working stress, and provided with means for positively limiting such movements.

l5. A tool shank having parts relatively movable under working stress, and provided with longitudinally disposed pins for limiting such movements.

GEORGE E. HACKETT.

Vitnesses D. HOWARD HAYwooD, LYMAN S. ANDREWS, J r. 

